Solutions for separating and singulating articles are known in which non-uniform articles loaded loosely into a feeder or hopper are poured continuously onto belts, rollers, and other types of mechanical conveyor, and are spread out into single units as they move along said conveyors. The spread-out articles can then be taken one-by-one so as to be put in series on a belt conveyor, for example. That type of spreading-out installation suffers from the drawback of being voluminous.
In the postal field, small parcels or packets are articles that are essentially non-uniform, namely articles that are of a wide variety of dimensions and shapes, and it is important to put them in series at a constant pitch, i.e. with a constant distance between the leading edges of any two consecutive articles, so that each article can be directed automatically and easily towards a respective sorting outlet of a sorting machine.